The invention relates to a surface-cleaning device comprising a base part and a cleaning part which is provided with a substantially flat contact surface for making contact with a surface to be cleaned and which is journaled so as to be rotatable relative to the base part about an axis of rotation which extends substantially perpendicularly to the contact surface.
The invention also relates to a vacuum cleaner provided with a housing in which a suction unit is present and with a suction attachment which is coupled to the suction unit via a suction channel and is provided with a surface-cleaning device, which surface-cleaning device comprises a base part and a cleaning part which is provided with a substantially flat contact surface for contact with a surface to be cleaned and which is journaled so as to be rotatable relative to the base part about an axis of rotation which extends substantially perpendicularly to the contact surface.
The invention further relates to a cleaning element suitable for use in a surface-cleaning device according to the invention.
A suction attachment of the Japanese brand National with type designation AMC-MS1 available on the Japanese market is provided with two surface-cleaning devices of the kind mentioned in the opening paragraphs arranged next to one another and is suitable for use in a vacuum cleaner of the kind mentioned in the opening paragraphs. FIG. 1a is a diagrammatic plan view of the known suction attachment 1, and FIG. 1b is a diagrammatic cross-section taken on the line Ibxe2x80x94Ib in FIG. 1a. The cleaning part 3 of the surface-cleaning devices 5 of the known suction attachment 1 comprises a disc-shaped holder 7 which is provided with a bearing journal 11 built up from elastic tongues 9. The holder 7 is detachably fastened to a bearing bush 13, which is accessible from a lower side 15 of the suction attachment 1, by means of the bearing journal 11 and is rotatably journaled in the bearing bush 13 relative to the suction attachment 1. A disc-shaped cleaning cloth 19 is fastened to a lower side 17 of the holder 7, on which cloth the contact surface 21, circular in shape, is present. The axis of rotation 23 of the cleaning part 3 encloses a small angle xcex1 of a few degrees with a perpendicular 27 on the surface 25 to be cleaned in an operational position of the suction attachment 1 on the surface 25 to be cleaned, so that a portion 31 of the contact surface 21 present adjacent a circumference 29 of the contact surface 21 of the cleaning cloth 19 is in contact with the surface 25 to be cleaned. When the suction attachment 1 is displaced over the surface 25 to be cleaned in a displacement direction X by a user, the cleaning parts 3 are rotated about their axes of rotation 23 in a direction R shown in FIG. 1a under the influence of friction forces F exerted on the parts 31 by the surface 25 to be cleaned. The rotating cleaning cloths 19 have a cleaning effect which supplements a cleaning effect provided by the suction attachment 1 as a result of an underpressure present in the suction attachment 1. Since the cleaning parts 3 of the known. suction attachment 1 are rotated under, the influence of said friction forces, the known suction attachment 1 need not have any driving means for driving the cleaning parts 3.
A disadvantage of the surface-cleaning devices 5 used in the known suction attachment 1 is that exclusively said portions 31 of the cleaning cloths 19 are in contact with the surface 25 to be cleaned. The result is that only a small portion of the surface 25 present below the suction attachment 1 is treated by the cleaning cloths 19. In addition, only an annular portion 33 of each cleaning cloth 19 extending along the circumference 29 is utilized for cleaning the surface 25, and a comparatively large central portion 35 of the cleaning cloth 19 remains unused.
It is an object of the invention to provide a surface-cleaning device and a vacuum cleaner of the kinds mentioned in the opening paragraphs wherein the cleaning part is also rotatable about the axis of rotation without driving means, but wherein the contact surface of the cleaning part is in substantially full contact with the surface to be cleaned.
To achieve this object, a surface-cleaning device according to the invention is characterized in that the cleaning part is pivotable relative to the base part about a pivot axis which extends transversely to the axis of rotation, while the base part is provided with means for exerting a pre-tension torque on the cleaning part about said pivot axis.
To achieve this object, a vacuum cleaner according to the invention is characterized in that the surface-cleaning device used therein is a surface-cleaning device according to the invention.
When the surface-cleaning device according to the invention is placed on the surface to be cleaned, the cleaning part is pivoted through contact with the surface to be cleaned about said pivot axis into a position in which the contact surface is directed substantially parallel to the surface to be cleaned and is accordingly in substantially full contact with the surface to be cleaned. Since said means exert a pre-tension torque on the cleaning part about the pivot axis, the contact surface exerts a surface pressure on the surface to be cleaned which is asymmetrical relative to the pivot axis, so that a displacement of the surface-cleaning device over the surface to be cleaned generates a friction force between the contact surface and the surface to be cleaned which is also asymmetrically distributed relative to the pivot axis. A suitable position of the pivot axis with respect to the axis of rotation of the cleaning part, for example a position in which the pivot axis intersects the axis of rotation or the pivot axis lies at a comparatively small distance from the axis of rotation, achieves that said friction force is also asymmetrically distributed with respect to the axis of rotation, so that the cleaning part is rotated about the axis of rotation under the influence of the friction force. Since the contact surface is in substantially full contact with the surface to be cleaned, the contact surface is substantially completely utilized for cleaning the surface to be cleaned during rotation.
A special embodiment of a surface-cleaning device according to the invention is characterized in that said means comprise a roller member which is rotatable about a further axis of rotation extending transversely to the axis of rotation and which bears with pre-tension on a roller track of the cleaning part, which roller track extends substantially parallel to the contact surface. A practical and simple construction of said means is obtained thereby, wherein wear of said means is limited as much as possible.
A further embodiment of a surface-cleaning device according to the invention is characterized in that said means comprise a wire spring, and the roller member is rotatably journaled around said wire spring adjacent an end of said wire spring. A practical and simple bearing for the roller member is thus provided, said means comprising only a limited number of components.
A yet further embodiment of a surface-cleaning device according to the invention is characterized in that the cleaning part is journaled with radial clearance in a bearing bush of the base part, and the base part is provided adjacent the bearing bush with a support ring which extends substantially perpendicularly to the axis of rotation and which serves to support the cleaning part in a direction parallel to the axis of rotation. Said support ring is provided, for example, on an end of the bearing bush. The use of said radial clearance renders the cleaning part pivotable about a support point which is present on the support ring approximately diametrically opposite a point of application of a pre-tension force arising from the pre-tension torque, as seen relative to the axis of rotation. The required pivoting possibility of the cleaning part is thus obtained by means of a particularly simple and practical construction.
A particular embodiment of a surface-cleaning device according to the invention is characterized in that the cleaning part is provided with a holder which is journaled so as to be rotatable about the axis of rotation relative to the base part, and with a cleaning element which is detachably fastened to the holder and is provided with the contact surface. This renders it possible to remove the cleaning element from the holder after use, for example in order to be cleaned or replaced with a new cleaning element.
A special embodiment of a vacuum cleaner according to the invention is characterized in that the suction channel comprises a suction tube which is pivotable about a pivot axis with respect to the suction attachment, which pivot axis extends substantially parallel to a front edge of the suction attachment and lies between the front edge and the axis of rotation of the cleaning part. When the suction attachment is moved over the surface to be cleaned, the user exerts a propelling force on the suction tube which usually comprises not only a horizontal component but also a vertical component and which is transmitted to the suction attachment at the area of said pivot axis. Since said pivot axis lies between the front edge of the suction attachment and the axis of rotation of the cleaning part, the suction attachment is supported by the front edge and the cleaning part in a stable manner, and undesirable rocking movements of the suction attachment under the influence of the vertical component of the propelling force are prevented.
According to the invention, a cleaning element suitable for use in a surface-cleaning device according to the invention, in which the cleaning part is provided with a holder with a detachable cleaning element, is characterized in that the cleaning element is provided at least with a first layer of cleaning cloth with a short-hair contact surface and a second layer of adhesive material for adhering the cleaning element to the holder. The cleaning element thus has a practical and simple layered structure. Since the contact surface is short-haired, a surface pressure distribution is obtained between the contact surface and the surface to be cleaned which leads to a particularly effective drive of the cleaning part about its axis of rotation.
A special embodiment of a cleaning element according to the invention is characterized in that the cleaning element comprises a third layer of support material interposed between the first layer and the second layer. The cleaning element as a result has a comparatively high stiffness, so that the cleaning element is easy to handle during its removal from the holder and its mounting on the holder.
A further embodiment of a cleaning element according to the invention is characterized in that the cleaning cloth is made from a microfiber material. A cleaning cloth manufactured from microfiber material is particularly suitable for use in a surface-cleaning device according to the invention because such a cleaning cloth was found to have a particularly good cleaning effect especially in the case of rotary movements of the cleaning cloth.
A yet further embodiment of a cleaning element according to the invention is characterized in that the adhesive material comprises velour for adhesion to a Velcro-like material provided on the holder. This allows the cleaning element to be provided on the holder in a particularly simple and reliable manner and to be detached from the holder in a particularly simple manner.